STL_WLM_QUERY

Contains a record of each attempted execution of a query in a service class handled by WLM.

STL_WLM_QUERY is visible to all users. Superusers can see all rows; regular users can see only their own data. For more information, see Visibility of data in system tables and views.

Some or all of the data in this table can also be found in the SYS monitoring view SYS_QUERY_HISTORY. The data in the SYS monitoring view is formatted to be easier to use and understand. We recommend that you use the SYS monitoring view for your queries.

Table columns

Column name	Data type	Description
userid	integer	ID of the user who generated the entry.
xid	integer	Transaction ID of the query or subquery.
task	integer	ID used to track a query through the workload manager. Can be associated with multiple query IDs. If a query is restarted, the query is assigned a new query ID but not a new task ID.
query	integer	Query ID. If a query is restarted, the query is assigned a new query ID but not a new task ID.
service_class	integer	ID for the service class. For a list of service class IDs, see WLM service class IDs.
slot_count	integer	Number of WLM query slots that a query uses according to the concurrency level set for the queue. Default is 1. For more information, see wlm_query_slot_count.
service_class_start_time	timestamp	Time that the query was assigned to the service class. This time is in the UTC time zone.
queue_start_time	timestamp	Time that the query entered the queue for the service class. This time is in the UTC time zone.
queue_end_time	timestamp	Time when the query left the queue for the service class. This time is in the UTC time zone.
total_queue_time	bigint	Total number of microseconds that the query spent in the queue
exec_start_time	timestamp	Time that the query began executing in the service class. This time is in the UTC time zone.
exec_end_time	timestamp	Time that the query completed execution in the service class. This time is in the UTC time zone.
total_exec_time	bigint	Number of microseconds that the query spent executing.
service_class_end_time	timestamp	Time that the query left the service class. This time is in the UTC time zone.
final_state	character(16)	Reserved for system use.
est_peak_mem	bigint	Reserved for system use.
query_priority	char(20)	The priority of the query. Possible values are n/a, lowest, low, normal, high, and highest, where n/a means that query priority isn't supported.
service_class_name	character(64)	The service class name. For more information about service classes, see WLM system tables and views.

Sample queries

View average query Time in queues and executing

The following queries display the current configuration for service classes greater than 4. For a list of service class IDs, see WLM service class IDs.

The following query returns the average time (in microseconds) that each query spent in query queues and executing for each service class.

select service_class as svc_class, count(*),
avg(datediff(microseconds, queue_start_time, queue_end_time)) as avg_queue_time,
avg(datediff(microseconds, exec_start_time, exec_end_time )) as avg_exec_time
from stl_wlm_query
where service_class > 4
group by service_class
order by service_class;

This query returns the following sample output:

 svc_class | count | avg_queue_time | avg_exec_time
-----------+-------+----------------+---------------
         5 | 20103 |              0 |         80415
         5 |  3421 |          34015 |        234015
         6 |    42 |              0 |        944266
         7 |   196 |           6439 |       1364399
(4 rows)

View maximum query time in queues and executing

The following query returns the maximum amount of time (in microseconds) that a query spent in any query queue and executing for each service class.

select service_class as svc_class, count(*),
max(datediff(microseconds, queue_start_time, queue_end_time)) as max_queue_time,
max(datediff(microseconds, exec_start_time, exec_end_time )) as max_exec_time
from stl_wlm_query
where svc_class > 5  
group by service_class
order by service_class;

 svc_class | count | max_queue_time | max_exec_time
-----------+-------+----------------+---------------
         6 |    42 |              0 |       3775896
         7 |   197 |          37947 |      16379473
(4 rows)